/*-------------------------------------------------------------------------
 *
 * sdir.h
 *      POSTGRES scan direction definitions.
 *
 *
 * Portions Copyright (c) 1996-2017, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * src/include/access/sdir.h
 *
 *-------------------------------------------------------------------------
 */
#ifndef SDIR_H
#define SDIR_H


/*
 * ScanDirection was an int8 for no apparent reason. I kept the original
 * values because I'm not sure if I'll break anything otherwise.  -ay 2/95
 */
typedef enum ScanDirection
{
    BackwardScanDirection = -1,
    NoMovementScanDirection = 0,
    ForwardScanDirection = 1
} ScanDirection;

/*
 * ScanDirectionIsValid
 *        True iff scan direction is valid.
 */
#define ScanDirectionIsValid(direction) \
    ((bool) (BackwardScanDirection <= (direction) && \
             (direction) <= ForwardScanDirection))

/*
 * ScanDirectionIsBackward
 *        True iff scan direction is backward.
 */
#define ScanDirectionIsBackward(direction) \
    ((bool) ((direction) == BackwardScanDirection))

/*
 * ScanDirectionIsNoMovement
 *        True iff scan direction indicates no movement.
 */
#define ScanDirectionIsNoMovement(direction) \
    ((bool) ((direction) == NoMovementScanDirection))

/*
 * ScanDirectionIsForward
 *        True iff scan direction is forward.
 */
#define ScanDirectionIsForward(direction) \
    ((bool) ((direction) == ForwardScanDirection))

#endif                            /* SDIR_H */
